Harvesting vaccines

Making a vaccine against a virus often involves growing large amounts of that virus. This is because a vaccine works by training your immune system to recognise the virus, and this recognition relies on markers on viruses called antigens. The viruses can be grown in and harvested from infected animal cells.

Viruses needed to make the influenza vaccine, for instance, are usually grown in chicken eggs. However, this takes time, is costly and in a flu pandemic it might not be able to keep up with public need. Using plants can enable faster antigen production on a massive scale. Eventually, this could produce the 50 million doses in 12 weeks that the US government thinks would be needed – an impossible feat using the traditional egg-based method. Trials are already going on for influenza vaccines made using tobacco plants (which were also used for the Ebola antibodies in ‘Fighting disease with pharming’).

Some scientists also talk about creating oral vaccines that could be consumed in plant-based foods. An early example is a hepatitis B vaccine grown in genetically modified potatoes. In 2005, researchers immunised people against hepatitis B by feeding them chunks of potato containing a single protein from the virus. Over half of these people then produced more antibodies against hepatitis B.

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